Chain link for a traction chain

ABSTRACT

PCT No. PCT/DE94/00110 Sec. 371 Date Aug. 2, 1995 Sec. 102(e) Date Aug. 2, 1995 PCT Filed Feb. 2, 1994 PCT Pub. No. WO94/18053 PCT Pub. Date Aug. 18, 1994A rotatable drive/support element having a support surface is used with a chain link having a hardened running surface extending in and adapted to ride in a travel direction on the support surface and a side surface also extending in the travel direction and normally out of contact with the element. The running surface has a predetermined width b and is formed of at least one edge region of an outwardly convex arcuate shape seen in the travel direction having a radius R of curvature and a respective corner region extending from the edge region to the side region and of an outwardly convex arcuate shape seen in the travel direction having a radius r of curvature. Herein r/b SIMILAR 0.05 to 0.11, and preferably R/b SIMILAR 2.4 to 3.1.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US national phase of PCT applicationPCT/DE94/00110 filed Feb. 2, 1994 with a claim to the priority of Germanapplication P 43 03 785.2 filed Feb. 10, 1993.

FIELD OF THE INVENTION

The invention relates to a chain link for a traction chain, for examplean offset model, conveyor chain, for example a straight model, or forsimilar chain types as well as a guide wheel for guiding and/ordeflecting or tensioning conveyor chains, transport chains, or similarchain models as well as a support roller for supporting and guidingtraction chains, transport chains, and/or similar types of chains aswell as guide rollers to ensure the rolling and force transmission inmechanisms using traction chains, transport chains, and or chain-likesystems and functions.

BACKGROUND OF THE INVENTION

Such elements are known in many types in the state of the art. With theknown elements the running surface region usually has a linear or nearlylinear shape so that nearly horizontal straight-line running surfacesare formed on the engaging surfaces of the parts. This construction iskinematically good mainly with regard to the movements between guidewheel, support roller, and chain link but this known construction ispoor with respect to optimal strength and wear in use. With elementsmade according to the known state of the art the pressures occurring inuse result in breaking-out or spalling of the edges in particular of thechain link due to the force distribution.

OBJECTS OF THE INVENTION

Starting from this state of the art it is an object of the invention toprovide elements of the described type wherein the pressures created innormal use are mainly directed along force vectors which run radially tothe running surface of the chain link or radially to the running surfaceof the guide wheel or of the support roller or running roller or thatare directed inwardly into inner regions of the guide wheel or supportroller, not however toward the edges of the running surfaces of thechain link, guide wheel, or running or support roller.

SUMMARY OF THE INVENTION

These objects are attained by a chain link usable a rotatabledrive/support element having a support surface. The chain link has ahardened running surface extending in and adapted to ride in a traveldirection on the support surface and a side surface also extending inthe travel direction and normally out of contact with the element. Therunning surface has a predetermined width b and is formed of at leastone edge region of an outwardly convex arcuate shape seen in the traveldirection having a radius R of curvature and a respective corner regionextending from the edge region to the side region and of an outwardlyconvex arcuate shape seen in the travel direction having a radius r ofcurvature. Herein r/b≅0.05 to 0.11, and preferably R/b≅2.4 to 3.1.

The combination wherein the running surface has adjacent the edge regiona noncurved region.

Since the running surface of the chain link is formed so that the forcesoccurring in use are directed generally radially to the pivot axis ofthe link or toward the interior of the link, a wear- and above allstrength-optimal shape is achieved or the shape forms itself at leastafter relatively short loading in use.

More particularly according to the invention R/b≅2.4 and r/b≅0.075 to0.11. In addition the entire running surface is of convex arcuate shapeseen in the travel direction. The running surface has two such sidesurfaces, two such edge regions adjacent the side surfaces, and two suchcorner regions each joining a respective one of the edge regions to therespective corner region. Furthermore the running surface is formedbetween the edge regions with a substantially flat center region.

In accordance with other features of the invention the two edge regionsjoin centrally on the running surface so that the entire running surfaceis arcuate. The support surface has a shape generally complementary tothe edge and corner regions of the running surface.

The permissible hardness of the running surface lies between 30 and 60HRc, preferably between 40 and 50 HRc, and the basic hardness of thechain link is set such that no substantial cross-sectional or surfaceflow takes place as a result of the pressure created by the runningroller, in particular with a permissible stretch-limit relationship orR_(e) /R_(m) of about 1, preferably with a yield-strength relationshipR_(e) /R_(m) of about 0.65 with particular attention to ensuring asufficiently plastic working possibility. Here R_(e) is the yieldstrength and R_(m) the tensile strength.

It is also preferably provided that the chain link is formed of standardmaterials, namely hardened steel, preferably with analysis valueswhereby manganese-sulfide formation is minimized with in particular whenmanganese steel is used a low sulfur content of less than 0.02%. In thismanner material fatigue is avoided.

It is particularly provided that the chain link is formed of alternativematerials, in particular with a hard-metal base, fiber-compositionmaterials, ceramic/ceramic compounds and/or technical ceramics,preferably based on Si₃ N₄ (silicon nitrate) with less than 15% byweight of sinter additive, a fracture growth in the subcritical regionwith a breaking strength KIC smaller than 20 MPa√m as well as similarmaterials such that the strength and the ductility are by means of theuse and proportions of suitable materials set to an optimal value forthe particular use of the chain link, with particular attention to thehomogeneity (Weibull modulus m) and m is greater than 10 m.

As a result of the construction according to the invention the use ofalternative materials is possible since these materials are as a resultof the shape used by the instant invention in a normal-load situationonly loaded with pressures that cannot be expected to crack out ordestroy the material.

In addition it is preferably provided that the compound convexly arcedcurve of the side flanks of the running surfaces are formed over theentire length or only in portions of the chain link with their radii Rand r preferably such that the parameter combination is R/bl≅2.4 to 3.1and r/bl≅0.05 to 0.11 or is optimized taking into account variouschain-link formations so that depending on the actual application anoptimal shape with respect to strength and/or wear is quicklyestablished automatically. The parameter bl here is determined dependingon the chain-link type and the particular link shape, this determinationtakes into account the shape of the part the running surface rides on(for example the shape of the running surface of the guide wheel or ofthe running roller) and the surfaces dependent thereon are paidattention to with respect to the forces effective on the side surfacesof the running-surface of the chain link.

The guide wheel, support roller and running roller according to theinvention are characterized by modified running-surface shapes which arederived from the special running-surface shape of the piece they run on(e.g. the chain link) and also correspond to a constant nonlinear(arced) function or nonlinear/linear curve combination. A linear ornearly linear curve shape (e.g. a straight line is effective for theoptimal technical/physical functioning of the pair of runningsurfaces--chain link/guide wheel or chain link/support or runningroller--taking into account the special running-surface shape of theother piece. e.g. the chain link, for particular technical uses ofrunning systems, conveyors, and chain systems of other constructions andfunction (e.g. high-speed systems, systems with special shockresistance, and the like) as particular embodiments of therunning-surface shape of the guide wheel or of the support or runningroller which is arranged at an angle to a normally horizontal runningsurface is advantageous when the size of the angle is preferablyselected that it can also be arranged in accordance with therequirements of the special running-surface shape of the other piece(e.g. chain link) a strength- and wear-optimal shape of the runningsurfaces and side guide surfaces of the guide wheel or the support orguide roller are established in use as soon as possible all bythemselves, in particular however a slope of 1:10 is realized or must bederived that these slopes of the running-part surfaces of guide wheels,support or running rollers are set for functional reasons in dependenceon the geometry of the entire pair of running surfaces and are notidentical with a purely accidentally occurring formation formed bycertain manufacturing processes (e.g. casting) on the running surfacesof guide wheels or of support or running rollers.

It can also be good for particular technical embodiments of chainsystems for strength- and/or wear-optimal reasons that the linear regionof the running surface of the guide wheel or of the support or runningroller that extends at an angle to an imaginary perpendicular to therunning surface is formed as a special combination of differently angledcurves (e.g. several straight lines at different angles to the imaginarystraight running surface), preferably so that it automatically andquickly establishes in use the wear- and strength-optimalrunning-surface shape of the guide wheel or of the support or runningroller taking into account the running-surface shape of the other pieceof the running-surface pair (e.g. chain link), it being particularlypreferable however with a curve combination of two straight sectionsrelative to a running-surface cross section transverse (90°) to thetravel direction (with outward slope of the running-surface shape)toward the edge inward is a linear or nearly linear segment of therunning-surface shape with a slope of 1:20 and wherein the straightportion directed to the guide wheel or support or running-roll edge issloped at 1:10 and in the opposite case of the slope (inward) this slopeis oppositely set up.

The formation according to the invention of chain link, guide wheel, andsupport roller can also be used all by itself and is advantageous, butis usable in combination with the corresponding construction of therunning surface of the chain link, the guide wheel, the running roller,and the support roller.

When complete chain segments comprised of two parallel chain links areput together and a corresponding chain is made of such chain segments,there is when for example it is used in the traction systems ofcaterpillar vehicles the effect that the entire chain segment takes atipped position on the running roller on the guide wheel so that onlythe outer region of one of the two chain links which form a chainsegment is directly in engagement with the carrying surface of the guidewheel or of the guide roller. If this is taken into account the objectof the invention is achieved in that the running-surface shape of thelink in cross section to the running-surface head transverse (90°) tothe travel direction only corresponds to a nonlinear function on theouter-lying running surface regions of a chain segment with two parallelchain links, preferably to a compound or logarithmically compoundconvexly arced curve as strength- and/or wear-optimal running-surfacegeometry, preferably over half to two thirds of the width of the runningsurface of each chain link so that the shape of this part of therunning-surface shape is particularly ideal in that it automaticallyestablishes in accordance with the basics of mechanics the least stressduring normal movement and use between a chain link while taking intoaccount the overall chain segment working together preferably with arunning roller over a long service life.

It is thus preferably provided that the running-surface shape in theregion of the running surface in which the nonlinear function is notrealized merges into another curve shape, preferably a linear or nearlylinear straight or nearly straight curve parallel or nearly parallel tothe opposite running surface (e.g. with respect to the standardembodiment of the running surface of a roller).

It can further preferably be provided that the edge of the runningsurface is formed in the region of the running-surface shape in whichthe nonlinear function is not realized by the transition radius,preferably in the parameter combination r/b≅0.05 to 0.11.

In an analogous manner the guide wheel can be so formed according to theinvention such that the shape of the running surface or of the runningsurfaces of the guide wheel correspond transverse (90°) to the traveldirection in cross section to a nonlinear function, preferably acompound or logarithmically concavely arced curve under the effect of anadequately curved opposite surface (e.g. the chain link) as a wearand/or strength-optimal rolling-surface geometry with respect to a part,e.g. half or two-thirds of the running surface, preferably the mirrorimage of the opposite running surface (e.g. that of the chain link) or amirror-similar shape (e.g. taking into account the running-surface widthof the guide wheel) and as determined on the basis of machinesautomatically establishes the least stress in normal movement between arunning surface, e.g. that of a guide wheel, and a corresponding otherpiece. e.g. a chain link with a long service life.

Since based on the possible tipped position of the chain segmentrelative to the running roller or to the guide wheel in practice ifpossible the formation of the running surface corresponding to anonlinear function or a compound shape first and mainly takes places onthe chain-link outer sides, it is preferably provided that for theconstruction and the delivery of these chain links the correspondingshape is not provided over the entire running surface transverse to thetravel direction, but only the respective chain link outer sides(relative to the chain segment) are provided in new condition with thenonlinear special compound arced surface shape. In this manner expenseis saved in manufacture without however substantially badly affectingthe desired performance

An analogous formation of the running surface can also be used in theconstruction of the support roller.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will become morereadily apparent from the following description, reference being made tothe accompanying drawing in which:

FIG. 1 is an elevational view of a standard prior-art chain link;

FIG. 1A is cross section taken along the line IA--IA of FIG. 1;

FIG. 1B is a cross section taken along line IB--IB of FIG. 1;

FIG. 1C is a side view in the direction of arrow IC of FIG. 1;

FIG. 2 is an elevational view through a prior art chain link in astraight model;

FIG. 2A is a section taken along line IIA--IIA of FIG. 2;

FIG. 2B is a side elevational view of the link of FIG. 2;

FIG. 2D is an elevational view of another prior-art link;

FIG. 2E is a section taken along line IIE--IIE of FIG. D;

FIG. 2F is a side elevational view of the link of FIG. D:

FIG. 3 is a cross section like FIG. 1A through an embodiment of a chainlink according to the invention;

FIG. 3A is a cross section like FIG. 1B through the link according tothe invention;

FIGS. 4 and 4A are larger scale views of details of respective FIGS. 3and 3A;

FIGS. 5 and 5A are views similar to FIGS. 4 and 4A but of anotherembodiment;

FIGS. 6 and 6A are views corresponding to FIGS. 3 and 3A of stillanother embodiment;

FIG. 7 is a cross sectional view through a hinge region of two chainlinks with a chain sleeve and a chain pin;

FIGS. 8 and 8A are views similar to FIGS. 3 and 3A showing a furthervariant;

FIG. 9 is a partial axial section through a guide wheel;

FIG. 10 is a view similar to FIG. 9 of a variant of the guide wheel;

FIG. 11 is a fragmentary elevational view illustrating a furthervariant;

FIG. 11A is a view similar to FIG. 10 of still another variant;

FIG. 11B is a fragmentary view similar to FIG. 11 showing amodification;

FIGS. 12, 13, 14, and 15 are views similar to FIG. 11 showing furthervariants of the guide wheel;

FIGS. 16, 16A and 16B are fragmentary views of support and guide rollersaccording to the invention in additional embodiments;

FIGS. 17, 17A and 17B are views similar to FIGS. 16, 16A and 16B ofstill other embodiments;

FIGS. 18, 18A and 18B show, in views similar to FIGS. 16, 16A and 16B,further embodiments;

FIGS. 19, 19A and 19B are views similar to FIGS. 16, 16A and 16B ofother embodiments;

FIGS. 20, 20A and 20B are also views similar to FIGS. 16, 16A and 16B ofstill other embodiments;

FIG. 21 is a diagram illustrating a drive condition of a chain segmentrelative to a guide roller;

FIG. 22A and 22B are views similar to FIGS. 3 and 3A showing runningsurfaces of a chain link according to a further embodiment;

FIG. 23 is a view similar to FIG. 10 showing a further embodiment of theinvention; and

FIG. 24 is a view similar to FIG. 16 of another support roller.

SPECIFIC DESCRIPTION

FIGS. 1A through 1C and 2A through 2F show the state of the art. Inthese prior-art embodiments of chain links the running surface region 1is shaped as a straight or nearly straight line, that is the runningsurface is in principle formed as a plane. This formation isdisadvantageous with respect to wear and strength.

In FIGS. 1A through 1C an offset chain link is shown while in FIGS. 2Athrough 2F a straight chain link is shown.

In the embodiment according to FIGS. 3 and 3A the running-surface shape2 of the chain link 3 seen in cross section to the running surface head(perpendicular to the travel direction) is shaped according to anonlinear function, in particular as a compound convexly arced surfacewhich corresponds to or is close to strength-optimal rolling-surfacegeometry.

In FIGS. 4 and 4A the shape of the compound curve running surface isdetermined by the parameter combination R/b of about 2.4 to 3.1 andr/b≅0.05 to 0.11 as a ratio of the radii of curvature of an edge region4 having the radius R to a corner region 2" having the radius r andterminating at a side surface 2'". In the embodiment according to FIGS.5 and 5A the same radii and parameter relationships are used in thecenter of the running-surface region and in the regions of the bolt orsleeve eye, with the running-surface shape correspondingly only in thelateral edge regions of the running-surface cross section to a shapecorresponding to a nonlinear function and then subsequently going overto a shape of a linear or nearly linear function (straight part 4).

In the embodiment of FIGS. 6 and 6A there is in an offset chain link 3the corresponding shape of the running surface 2 both in the centralrunning-surface region (FIG. 6A) as in the region of the bolt eye (FIG.6).

In the embodiment according to FIG. 7 there is in an offset chain link 3a hinge region with the chain link 3 completed with a chain sleeve 5 anda chain bolt 6. Thus the desired shape of the running surface 2 is suchin the region of the bolt or sleeve eye, thus in the hinge regionbetween two chain segments, that in this region the desiredrunning-surface shape 2 is formed over the entire cross section of twochain links 3.

In the embodiment according to FIGS. 8 and 8A the shapes of the sideflanks 8 to both sides of the running surface 2 of the chain link 3 arealso a compound convexly arced curve region in the above-givensize-order regions and relationships of the radii R and r.

In FIGS. 9 through 15 a guide wheel 9 is shown for guiding and/ordeflecting or tightening track chains, transport chains, or similarchain types. To this end the shape of the running or support surface 10of the guide wheel 9 transverse to the travel direction in cross sectioncorresponds to a nonlinear function, in particular a compound convexlyarced curve which corresponds to or is close to a strength- and/orwear-optimized rolling-surface geometry.

As in particular visible from FIG. 11 the radii R and r of the compoundconvex curvature of the running surface are characterized by theparameter combinations R/b of about 2.4 to 3.1 and r/b≅0.05 to 0.11. Theparameter b thus is dependent on the shape of the other part, that isfor example on the chain link running on the running surface 10 of theguide wheel 9 and of the thereto related force transmission to therunning surface 10 of the guide wheel 9.

As visible in FIG. 11A the nonlinear curve of the shape of the runningsurface 10, preferably the compound convexly curved shape, can only becreated in part, that is the edge radii, for example the edge radius ras well as the running surface radius R are set such that they mergeinto a linear or nearly linear curve shape of the running-surface shape,for example a straight region 11. The linear or nearly linear curveshape of the running surface 10 can also be set in a corner to apresumed horizontal running surface as in FIG. 11A on the left (See alsoFIGS. 18A and 18B.) with the angle preferably so chosen that the wear-and strength-optimal running surface is set by itself as quickly aspossible in use while taking into account the special running-surfaceshape of the other part of the running surface pair (e.g. the chainlink), in particular set with an inclination of 1:10.

The imaginary straight line of the running surface is thus shown in adashed line and the respective facing inclined surface in solid lines.

As also shown in FIG. 11B, (and in FIGS. 18A and 18B) the linear ornearly linear curve shape can also be formed as a combination of curveswith different inclinations wherein two combined straight or nearlystraight sections with one section 10a (16a in FIGS. 18A and 18B) at1:20 and the section 10b (16b in FIGS. 18A and 18B) at 1:10. The same istrue for the support roller and running roller. According to FIG. 12 theshape of the lateral guiding surfaces 12 of the central flange of thewheel 9 corresponds to a compound concavely arced curve with the radii Rand r of the compound arced curve preferably at the ratio of R to b1 ofabout 2.4 to 3.1 and r/b1 about equal to 0.05 to 0.11.

As also shown in FIG. 13 the compound concavely arced shape of thelateral guiding surfaces 12 of the central flange of the guide wheel 9can be only partially formed, with the edge radius r and therunning-surface radius R such that they merge into a linear or nearlylinear function of the shape of the lateral guiding surfaces 12 of thecentral flange of the guide wheel 9. The straight regions are shown at13.

As visible from FIGS. 14 and 15 the nonstraight preferably compoundconcavely arced shape of the running surface 10 of the guide wheel 9 aswell as the similarly curved shape of the side guiding surfaces 12 ofthe central flange of the guide wheel 9 are combined with each othersuch that both curve shapes whether of a nonlinear base (see FIG. 14) oreven combined with linear or nonlinear bases (see FIG. 15) merge intoone another such that a strength- and/or wear-optional overall shape isproduced and the radii R and r of the compound concavely arced over-allshape are characterized by the above-described dimensional relationship.

FIGS. 16 to 20 finally each show a support roller 14 for supporting andguiding traction chains, transport chains, or similar types of chains orusable as a guide roller for ensuring the rolling function and transferof force to traction chains, transport chains, and/or similar chain-likethings becoming necessary with the running mechanism. Even herein theshape of the running surfaces 15 of the support or running roller 14correspond seen perpendicular to the travel direction in section to acompound concavely arced curve (as in particular visible in FIG. 16).With respect to FIGS. 17, 17A, and 17B, the radii R and r of thecompound concave curve of the running surface are preferablycharacterized by the parameter relationship R/b≅2.4 to 3.1 and r/b≅0.05to 0.11.

The parameter b is thus to be quantified by the shape of the other part,that is for example of the chain link riding on the running surface ofthe support or running roller 14 and the associated force applied to therunning surface.

As in particular visible in FIGS. 18, 18A, and 18B the nonstraight curveshape of the contour of the running surfaces 15 is only partiallyemployed, that is the edge radii, for example the edge radius r, as wellas the running surfaces radii, for example the running-surface radius R,are set such that they merge into a linear or nonlinear function of therunning-surface shape, for instance a straight line 16.

Here the same embodiments as above are described with reference to therunning surface of the guide wheel, in FIG. 18 the running-surfaceshapes 16a and 16b.

In the embodiment according to FIGS. 19, 19A, and 19B the shapes of theside guiding surfaces 17 of the rim of the support or running roller 14are conformed in cross section to a nonlinear function, in particular acompound concavely arced curve where the radii R and r of the compoundarced curve are formed by the relationship R/bl≅2.4 to 3.1 and r/bl≅0.05to 0.11.

FIGS. 20, 20A, and 20B show how the nonlinear preferably compound arcedshape of the side guiding surfaces at the edges of the support orrunning roller 14 are only partially formed, that is the edge radii, forexample the edge radius r, as well as the running-surface radii, forexample the running-surface radius R, are chosen so that they merge intoa linear or nearly linear function 18 of the shape of the side guidingsurfaces of the edges of the support or running roller 14. In thismanner the nonlinear, preferably compound arced shape of the runningsurfaces of the support and running rollers 14 and the correspondingshape of the side guiding surfaces 17 are combined such that both curvesmerge into one another on a purely nonlinear bases as well as on acombined linear/nonlinear basis.

FIG. 21 shows the possible tipped position of a chain segment relativeto a support roller 14. The chain-link segment thus is formed by twochain links 3 which are connected to each other by a chain sleeve 5 or achain bolt. According to FIG. 21 it is possible that the chain segmentassumes a tipped position relative to the support roller 14 or evenrelative to the guide wheel. In FIG. 21 one possible position is shownin solid lines while the other possible tipped position is shown by adashed line 19. In a construction with a traveling chain, guide wheeland running wheel as customarily used in a tracked caterpillar drivewhen there is a tipped position as shown in FIG. 21, this means thatduring use of such a chain segment the compound shape will at first orexclusively be formed by the outer sides of the chain links. As a resultof this possibility a preferred construction is that the chain link isprovided corresponding to FIGS. 22A and 22A only on the chain-link outerside (in FIGS. 22A and 22B upper right) with nonlinear preferablycompound convexly arced running-surface shapes 2. In this manner whenthere is produced in region 2 a strength- and/or wear-optimalrunning-surface geometry in a partial region of the running-surfaceshape, this running-surface shape 2 extends over half to two-thirds ofthe width of the running surface of the chain link 3. The remainingregion which is indicated with arrow 20 is formed otherwise, preferablyas a straight or nearly straight surface which preferably is formedparallel or nearly parallel to the opposite running surface of thesupport roller of the guide wheel. Preferably this region is straightand extends substantially parallel to the pivot axis of the chain linkwhich is shown at 21. Even in this arrangement the relationships of thetransition radius r relative to the width b of the entire runningsurface is such that the relationship r/b is about equal to 0.05 to0.11.

The corresponding formation in a guide wheel 9 is shown in FIG. 23. Herethe shape of the running surfaces or the running surfaces 2 of the guidewheel 9 is formed transverse (at 90°) to the travel direction in crosssection to a nonlinear function, preferably a compound orlogarithmically concavely arced curve corresponding to the adequatelycurved opposite running surface of the chain link 2 as wear- and/orstrength-optimal geometry with this particular formation of the runningsurface being made only in the relatively outer-lying regions of therunning surface 2 of the guide wheel 9, in fact over from half totwo-thirds of the width of the running surface. This surface correspondsgenerally to the mirror image of the opposite running surface of thechain link 2 or is at least generally mirror symmetrical or similar tothis shape. The corresponding shape is worked into the new part, thisshape corresponding to a shape which will give a longer service lifeaccording to the invention.

Even here the relationship of radius R to the width of the correspondingrunning surface b and the transition radius r relative to the width ofthe running surface b is done in the manner laid out above.

FIG. 24 shows the same relationships with reference to a running roller14. Here the corresponding shape formation is only provided in theregion 2 of the running surface while the region 20 can also be formedas in the above-described embodiments, in particular straight andparallel to the pivot axis 22 of the running roller or of the guidewheel.

The invention is not restricted to the illustrated embodiments but canbe varied widely within the scope of the disclosure.

All new individual or combination features described in the descriptionand/or the drawing are considered important to the invention.

We claim:
 1. In combination with a rotatable drive/support elementhaving a support surface, a chain link having a hardened running surfaceextending in and adapted to ride in a longitudinal travel direction onthe support surface and a side surface also extending in the traveldirection and normally out of contact with the element, the runningsurface having a predetermined width b and being formed ofat least oneedge region having an outwardly convex arcuate shape seen in the traveldirection having a radius R of curvature; and a respective corner regionextending from the edge region to the side surface and of an outwardlyconvex arcuate shape seen in cross section having a radius r ofcurvature,wherein r/b≅0.05 to 0.11.
 2. The combination defined in claim1 wherein R/b≅2.4 to 3.1.
 3. The combination defined in claim 1 whereinthe running surface has adjacent the edge region a noncurved region. 4.The combination defined in claim 1 wherein R/b<2.4 and r/b≅0.075 to0.11, the entire running surface being of convex arcuate shape seen incross section.
 5. The combination defined in claim 1 wherein the runningsurface has two such side surfaces, two such edge regions adjacent theside surfaces, and two such corner regions each joining a respective oneof the edge regions to the respective corner region.
 6. The combinationdefined in claim 5 wherein the running surface is formed between theedge regions with a substantially flat center region.
 7. The combinationdefined in claim 5 wherein the two edge regions join centrally on therunning surface, whereby the entire running surface is arcuate.
 8. Thecombination defined in claim 1 wherein the support surface has a shapegenerally complementary to the edge and corner regions of the runningsurface.
 9. The combination defined in claim 1 wherein the runningsurface has a hardness between 30 HRc and 60 HRc.
 10. The combinationdefined in claim 1 wherein the running surface has a hardness between 40HRc and 50 HRc.
 11. The combination defined in claim 1 wherein therunning surface is made of a manganese-steel alloy.